Ghebrab Tewodros Tekeste
Civil Engineering, Jimma University Institute of Technology, P.O. Box 378, Jimma, Ethiopia.
Civil, Environmental, and Construction Engineering, Texas Tech University, Lubbock, TX 79409-1023, USA.
Materials (Basel). 2020 Feb 12;13(4):840. doi: 10.3390/ma13040840.
The effect of mill-rejected granular cement (MRGC) on enabling concrete to autogenously heal its cracks was investigated. The crack-healing efficiency of concrete containing 5%, 10%, 15%, and 20% wt. of MRGC as a replacement for natural fine aggregate was investigated at the age of 28 days. Concrete specimens were induced with artificial cracks and placed in water or air at 20 ± 2 °C to cure and heal the cracks for an additional 28 days. Compressive, flexural, and tensile strengths and water permeability tests were carried out to evaluate crack-healing by evaluating the strength to regain and the reduction in water permeability of concrete. For the air-cured specimens, the gain in compressive strength was between 45% and 79%, the flexural strength was between 74% and 87%, and the tensile strength was between 75% and 84% of the reference specimens for the MRGC content was between 0% and 20%, respectively. For the water-cured specimens, the gain in compressive strength was between 54% and 92%, the flexural strength was between 76% and 94%, the tensile strength was between 83% and 96% of the reference specimens for the MRGC content between 0% and 20%. The water permeability coefficients of the concrete specimens cured in water after cracking decreased by one order of magnitude, while those of the specimens cured in the air increased by the same order of magnitude. The crack-healing efficiency of concrete could be enhanced by increasing the MRGC content of concrete and hydration water.
研究了磨细废弃粒化水泥（MRGC）对混凝土自愈合裂缝的影响。研究了用5%、10%、15%和20%重量的MRGC替代天然细骨料的混凝土在28天龄期时的裂缝愈合效率。对混凝土试件施加人工裂缝，然后置于20±2℃的水中或空气中养护28天，以使裂缝愈合。通过评估混凝土强度的恢复和水渗透性的降低来进行抗压、抗弯和抗拉强度以及水渗透性试验，以评价裂缝愈合情况。对于空气养护的试件，当MRGC含量在0%至20%之间时，抗压强度的增益在45%至79%之间，抗弯强度在74%至87%之间，抗拉强度在75%至84%之间，分别相对于参考试件。对于水养护的试件，当MRGC含量在0%至20%之间时，抗压强度的增益在54%至92%之间，抗弯强度在76%至94%之间，抗拉强度在83%至96%之间，相对于参考试件。开裂后在水中养护的混凝土试件的水渗透系数降低了一个数量级，而在空气中养护的试件的水渗透系数增加了一个数量级。通过增加混凝土中MRGC的含量和水化水，可以提高混凝土的裂缝愈合效率。
